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Old November 14, 2019, 20:15   #1
stimpsonjcat
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New form 1 can build starts...

Drawing:


If you look at the drawing you will see a triangular cross section near the leading edge of the cone. I did that as a means of holding the baffle for cutting the other side using collets to make adjusting/loading easier for that side. Worked great. I will hand scallop that section to be a sort of spiral pattern after I get all the baffles cut.


Here's the test baffle being held in the 1" collet for cutting the downstream concave cone using a boring bar:


The 303 stainless cuts very well with both carbide and HSS.
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Old November 16, 2019, 06:50   #2
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718 not so much!!

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Old November 23, 2019, 18:53   #3
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I am pretty happy with that.

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Old November 24, 2019, 19:07   #4
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OK, here are my efforts at spot-welding the can parts together today. It's bad.



The welder is doing something odd today and it's not helping my 'technique' any. It intermittently won't throw a spark when I press the pedal.

I am usually a passable TIG welder, and some welds went the way I wanted them to. Not as tight as I'd like, but on the seam and decent penetration.

I played with some scrap tubing last week and various amperages and things went pretty good...sigh.

One thing that happened was I had a blowout. Not a burn-through...a blow out. Kinda freaked me out and left a giant ball on the electrode. Then it happened again when I went back to do the second set of tack-welds and my brain finally stared at the situation and said "It's getting hot, and you didn't give it anyway to vent." So I pulled the mandrel out and ground a flat down the full side to let the internal gases escape. No more blowouts.

But the main problem is I have a misalignment when test-fit on the rifle. I am going to go ahead and finish the welds up and then probably use the mandrel backwards in the lathe to see if I can sort out the issue and correct it.

Stay tuned for moar train-wreck!
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Old November 24, 2019, 19:51   #5
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Now that you have it spot welded, you could chuck it up in the lathe on super slow speed and try to tig it that way. The welds may come out better.

Just a suggestion of course.

Also wanted to subscribe so I can see how the scallop cuts on the face of the baffles do a redirecting the gas.
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Old November 24, 2019, 20:09   #6
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Quote:
Originally Posted by John A View Post
Now that you have it spot welded, you could chuck it up in the lathe on super slow speed and try to tig it that way. The welds may come out better.

Just a suggestion of course.

Also wanted to subscribe so I can see how the scallop cuts on the face of the baffles do a redirecting the gas.
Hot-shop and cold-shop are separated.
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Old November 25, 2019, 12:32   #7
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That is a lot of welding to do. You might want to preheat the piece prior to welding, do a little at a time and then place back in the oven to normalize to prevent warping.

Cobbling together a rotissary rig by your welder could be worth the effort. You already have the mandrel set up. Take a look at this video for some ideas.

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Old November 25, 2019, 12:42   #8
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Quote:
Originally Posted by John A View Post
Now that you have it spot welded, you could chuck it up in the lathe on super slow speed and try to tig it that way.
Welding in a lathe is not recommended as the current passes through the head stock bearings.
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Old November 25, 2019, 13:35   #9
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can

If welded how do you clean the inside of the baffles?
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Old November 26, 2019, 14:31   #10
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Quote:
Originally Posted by tac-40 View Post
That is a lot of welding to do. You might want to preheat the piece prior to welding, do a little at a time and then place back in the oven to normalize to prevent warping.

Cobbling together a rotissary rig by your welder could be worth the effort. You already have the mandrel set up. Take a look at this video for some ideas.

Yes yes...building a jig will almost certainly speed up completion of this project.
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Old November 26, 2019, 14:32   #11
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Quote:
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If welded how do you clean the inside of the baffles?
You don't.

This is actually the norm in suppressors.
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Old November 26, 2019, 14:38   #12
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Much better welds last night after lowering the amps, increasing the electrode nose length, and enabling the pulse feature.

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Old November 30, 2019, 16:23   #13
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Got new purple electrodes yesterday, and the batteries for the deluxe helmet.

Today went great. Ended up using a 1/16" electrode and running 50 amps with a 10Hz pulse.

The welds from today were about half the width of the previous welds, and were the right colors.

Waiting for it to cool to see if the misalignment got better or worse.

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Old December 01, 2019, 08:59   #14
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Considering if there is no major warpage, I'm curious how those thunderbeast'ish scallops are going to sound.
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Old December 01, 2019, 21:34   #15
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Got a spacer made this morning to 'fix' the misalignment on the can. I made this out of the portion of bbl I cut off the rifle earlier. Basically it is a cylinder turned to mate ver closely with the OD of the bbl where I turned it back for the other 308 can. But then I ground one of the faces at a slight angle vs the axial angle. This has the effect of pushing the can against the thread-form so I can move the outboard hole towards centerline. It worked, and I added some indexing marks to make it repeatable...and tested repeatability.



Here's the muzzle end after getting the alignment right.



The can is so wide the rifle can balance on it:



I took it to the range and it is hearing-safe IMO...no ringing. I could hear the bullet impacting the frame/berm after the sonic CRACK.

Here is the rifle after I got home and rattle-canned it.



I'll try to work up some subsonic ammo for it. Anyone have any pet loads that have worked for a 1:10 bbl?
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